Comments by Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 11 December 2023

    Hi, jim,

    Where are you not finding 2-3 Ah AA batteries? I just typed "AA NiMH" in to Amazon and they're all in that range.

    - Jan

  • Servo control interface in detail

    Servo control interface in detail

    - 16 December 2022

    Hi, Geert.

    I am not aware of any manufacturer references, though I have not looked around lately. I think higher-end manufacturers offer whole systems and make sure their products work together; they do not have much incentive to publicize what they would consider internal details that just make it easier for their products to get copied.

    In any case, 3.3V-5V microcontroller outputs with a 150-220 ohm resistor in series (for some short protection on the line) generally work, so you can make your control signal like that and you should be fine. If you have a particular servo and application like the 12V thing you mentioned and are concerned about your margins, it should be quite easy to throw it on a scope, vary your control signal, and see where the actual thresholds are.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 24 April 2022

    Hi, Jana.

    Different battery types have different maximum discharge rates, which is how fast you can effectively get that energy out of the battery. The maximum discharge rate is also generally proportional to capacity, so a bigger battery of the same type will be able to deliver more current. A tiny battery like your 12V one will not be able to deliver much current, which is why your motor isn't turning very fast.

    You could use a meter to measure how much current the motor is drawing when it's turning the way you want it to (with the eight AA in series), but most likely you'll be fine with a 1A adapter, which are available all over (e.g. https://www.pololu.com/product/1471 ). 1 A is 1,000 mA, and that's a current rating, not capacity, which is current multiplied by time (Ah or mAh, where the h is hours).

    - Jan

  • New products: DRV8256E/P motor driver carriers

    New products: DRV8256E/P motor driver carriers

    - 7 March 2022

    Hi, Don,

    Thanks for the elaboration. Why so much negativity? (If you thought you wrote something worthwhile, why would you preemptively say you'll delete your post?) Have we done something besides posting technical information that you think is incorrect?

    A lot of your ire seems directed at the alleged nonsense of "disabling the whole chip, at PWM frequencies", which is not what we are suggesting. You can see on page 7 of the datasheet under Recommended Operating Conditions that the EN input is one of the inputs intended to have PWM applied.

    And you have heard of sign-magnitude control, right? I am not sure why you are calling it "the Pololu way" when it's a common approach that has a well-established name. While TI's datasheet does not specifically recommend one pin over another for PWM, other similar chips, such as MAX14870, literally call their pins "PWM" and "DIR", with the PWM pin corresponding to the TI "EN" pin on this chip in terms of functionality. And the DRV8256 E and P versions remain anomalous relative to TI's other motor drivers that have similar pairs of versions.

    - Jan

  • Why we don't have comments on our product pages

    Why we don't have comments on our product pages

    - 24 August 2021

    Hi, Pamela,

    Thanks for your feedback. Do you have any suggestions for addressing the problems I discussed, e.g. with the Lowe's blowtorch? Also, can you give me an example of the kind of post you would like to leave and on which product page(s)?

    - Jan

  • Firmware update for Tic Stepper Motor Controllers, with new features including limit switches and homing

    Firmware update for Tic Stepper Motor Controllers, with new features including limit switches and homing

    - 6 May 2021

    Hi, Ramon.

    We do not have specific plans for it, but Maxim acquiring Trinamic might make them a little more attractive. Is there some particular part (or parts) that you would recommend for the first one to use in a Tic?

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 30 December 2020

    Hi, Marilyn.

    As far as the basic physics, the 2000 mAh battery is going to have about 10% more capacity than an 1800 mAh battery with the same 3.7V. However, safety is a whole separate issue. For example, you could have two batteries with the same specs as far as voltage and capacity but one could be prone to starting fires and the other not. Also, the whole system including the charging circuit could affect the safety and reliability, so you would have to be quite familiar with the details of all the parts and how they are connected to be sure you have something safe. But I suspect the particular parts for the handwarmer are going to be pretty basic and unsophisticated, and 10% is not much of a difference, so chances are you would be fine. If you do try it, maybe do the charging in some place where you won't set the house on fire if the battery starts burning.

    - Jan

  • New products: Magnetic Encoder Pair Kit with JST SH-type Connectors for Micro Metal Gearmotors

    New products: Magnetic Encoder Pair Kit with JST SH-type Connectors for Micro Metal Gearmotors

    - 8 December 2020

    Hello, Regis.

    Is your dI/dt concern based on some problems you have seen, or is it just a general theoretical question? I do not recall ever seeing a resistor in line with the cap, so I suspect the common consensus/wisdom is that added resistors would not be solving a real problem while possibly reducing the effectiveness of the caps for their spark noise suppression purpose.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 28 August 2020

    Hi, Dave.

    Sorry to hear about your golf cart. Unfortunately, your problem sounds like it doesn't have anything to do with the topic of this post and is instead just about troubleshooting the details of your control board, so I cannot help you with that. If you cannot get any information about your particular board, the main general advice I have is to try to get your hands on a thermal imager (they're getting cheaper and more ubiquitous all the time) and look for parts that heat up over those 1.5 hours of operation.

    - Jan

  • Understanding battery capacity: Ah is not A

    Understanding battery capacity: Ah is not A

    - 24 August 2020

    Jason,

    I think you should just use one of those portable power banks (or "portable chargers" or "external phone battery pack") that already has USB ports built into it. There are so many sizes available and basic ones are so cheap now ($20 or less). Regarding the battery chemistries, sure, the secondary battery can be a different type than your main one as long as the electronics in between do the right thing.

    - Jan

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